Handling runtime exceptions in Java

I have the following code

try{//do something
     }
  catch (Exception e) {
        log.error(e,e);
        if (e instanceof RuntimeException) {
            throw (RuntimeException) e;
        } else {
            throw new RuntimeException(e);
        }
    }

The findbugs Stataic analyzer throws this warning

What I don't understand is that its exception is caught instead of runtimeException. Why this warning?

Solution

You can also try the following code This will be better read and maintained

try{//do something
}
catch (RuntimeException e) {
    throw e;
} 
catch (Exception e) {
    throw new RuntimeException(e);
}